Firefighters and other safety personnel use various types of equipment when fighting a fire. This equipment typically includes a coat, boots, gloves and other clothing specially created to protect against fire and heat as well as a self contained breathing apparatus to provide oxygen. Although such equipment provides some protection, firefighter's still face significant dangers including the danger of a flashover. In general, once the ambient temperature in a fire reaches about 600 degrees Fahrenheit, the temperature will quickly rise to over 1100 degrees Fahrenheit. At this point, a flashover can occur in which the air ignites and kills or severely injures firefighters. Thus, it is unsafe to fight fires once the ambient temperature reaches around 600 degrees Fahrenheit.
To alleviate some of the dangers involved in firefighting, various electronic devices have been developed to provide warnings to firefighters. For example, U.S. Pat. No. 5,640,148 discloses a dual activation alarm system for a personal alert safety system (PASS). U.S. Pat. No. 5,635,909 discloses a temperature monitoring assembly that is incorporated into a garment such as a coat. This device includes a speaker to provide an audible alarm. U.S. Pat. No. 5,541,549 discloses a personal alarm safety system that is designed as part of the firefighter's belt. Further, U.S. Pat. No. 5,137,378 discloses an integrated firefighter safety monitoring and alarm system that provides a number of warnings to a firefighter. This system includes temperature monitoring and provides an audible alarm. The system also has a display for providing additional information to the firefighter including a visible warning. The system is contained in a case that can have a belt or mounting clip for attaching to the firefighter's equipment.
However, even with such conventional devices, firefighters are still injured or killed by flashovers. The complexity of the conventional devices, the difficulties of the firefighting environment and the type and location of the warnings cause firefighters not to hear audible warnings or not to see visible warnings of dangerous ambient temperatures.